For gas logs in an open fireplace the handheld remote and receiver box that sits outside the hearth have batteries. We suggest changing out both of them as it is a common reason for remote problems. The handheld will take A13 and the reciever will need 4 AA batteries. To change the batteries in the reciever box replace them one at time and press the remote in-between changes to ensure it stays connected.
Another common issue could be your pilot light is out. It must be re-lighted for the remote to function.